The layers above would be not as old and the layers below would be the older layers.
Rotator cuff
The rotator cuff is a group of muscles that perform a variety of tasks such as flexion, abduction, internal rotation and external rotation. The muscles in this group are essential to all movement of the shoulder, making them very essential for upper body mobility. Namely, the muscles of the rotator cuff are supraspinatus, infraspinatus, teres minor and subscapularis.
